Background
Doppler-derived hemodynamic data for normal tricuspid mechanical valve prostheses are limited.
Methods
A comprehensive retrospective Doppler echocardiographic assessment of 78 normal St. Jude Medical Standard (St. Jude Medical, Inc., St. Paul, MN), CarboMedics Standard (CarboMedics, Inc., Sorin Group, Burnaby, British Columbia, Canada), and Starr-Edwards (Edwards Lifesciences, LLC, Irvine, CA) mechanical tricuspid valve prostheses was performed early after implantation. We used all the important Doppler-derived hemodynamic variables reported to date, including peak early diastolic velocity (E velocity), mean gradient, pressure half-time, time velocity integral of the tricuspid valve prosthesis (TVI TVP ), and ratio of the time velocity integral of the tricuspid valve prosthesis to the time velocity integral of the left ventricular outflow tract (TVI TVP /TVI LVOT ).
Results
The mean values obtained for the Doppler parameters did not differ significantly when the measurements from five or nine consecutive cardiac cycles were averaged. Pressure half-time was <130 msec in all 43 patients with St. Jude Medical Standard and CardioMedics Standard prostheses in whom it could be measured. Mean gradient <6 mm Hg, E velocity <1.9 m/s, TVI TVP <46 cm, and TVI TVP /TVI LVOT <2.1 were recorded in 59 (87%) of the 68 patients with either of these prostheses. Hemodynamic variables were considerably less favorable in patients with Starr-Edwards prostheses.
Conclusion
These calculated threshold values (mean + 2 SD) are useful for identifying normal tricuspid mechanical valve function. Prostheses with values for hemodynamic variables that are outside the mean + 2 SD parameters that we have calculated are most likely to be dysfunctional. However, in rare cases, mechanical tricuspid valve prostheses may be dysfunctional even when their hemodynamic parameters are within these specified ranges because of small body surface area or other factors.
The preferred method for assessing prosthetic valve function is two-dimensional echocardiography combined with Doppler. Doppler-derived measures that are clinically useful in the assessment of hemodynamic properties for mechanical tricuspid valve prostheses have been published, but such data are available for only a few prostheses and assessments comprise only mean gradient (MG), peak early tricuspid diastolic velocity (E velocity), and pressure half-time (PHT).
Clinically useful Doppler parameters for evaluating mitral valve function, such as ratio of the time velocity integral of the mitral valve prosthesis to the time velocity integral of the left ventricular outflow tract (TVI MVP /TVI LVOT ), effective orifice area (EOA), and indexed effective orifice area (IEOA), have been documented in numerous studies, including several from our own institution. Reference (normal) values for the time velocity integral of the tricuspid valve prosthesis (TVI TVP ), the ratio of the TVI TVP to the time velocity integral of the left ventricular outflow tract (TVI TVP /TVI LVOT ), EOA, and the IEOA have recently been established for several tricuspid valve bioprostheses but not for mechanical tricuspid valve prostheses.
We hypothesized that these same variables might be useful in assessing normal mechanical tricuspid valve prostheses. The purpose of this retrospective study, therefore, was to define normal mechanical tricuspid valve prosthesis function in the early postoperative period for the St. Jude Medical Standard (SJM; St. Jude Medical, Inc., St. Paul, MN), the CarboMedics Standard (CM; CarboMedics, Inc., Sorin Group, Burnaby, British Columbia, Canada), and the Starr-Edwards (SE; Edwards Lifesciences, LLC, Irvine, CA) prostheses by using all the important Doppler-derived hemodynamic variables described in the medical literature for mitral valve prostheses.
Materials and Methods
The study was approved by the Mayo Clinic Institutional Review Board. All study patients provided written informed consent to allow the use of their medical records for research purposes. No industry support was provided.
Patient Selection
From the cardiac surgical database of Mayo Clinic, Rochester, Minnesota, we identified 763 patients aged 18 years or older who underwent tricuspid valve replacement between January 1, 1993, and December 31, 2007. A total of 157 of these patients had mechanical tricuspid valve prostheses implanted. Of these 157 patients, 89 (57%) received SJM valves, 45 (29%) received CM valves, and 23 (15%) received SE valves. Seventy-nine patients who met the prespecified exclusion criteria were omitted from the study: Thirteen patients died within 30 days of surgery, 5 patients did not undergo intraoperative transesophageal echocardiography (TEE), 7 patients did not have transthoracic echocardiography (TTE) performed within 30 days of surgery, 2 patients had signs of possible tricuspid prosthesis stenosis or regurgitation on intraoperative TEE or postoperative TTE, 11 patients were on vasopressors at the time of the postoperative TTE, 8 patients had heart rate ≥100 beats/min, 32 patients had inadequate images for obtaining accurate and complete Doppler data on the postoperative TTE, and 1 patient underwent a Glenn procedure and was excluded because of the potential effects of this procedure on tricuspid valve hemodynamic properties. The remaining 78 patients constituted the study population: 51 patients with SJM prostheses, 17 patients with CM prostheses, and 10 patients with SE prostheses.
Prosthesis function was determined to be normal if the following three criteria were met: 1) normal postoperative valvular heart physical examination; 2) normal appearance of the prosthesis on intraoperative TEE; and 3) normal appearance of the prosthesis on TTE performed within 30 days of surgery. No patient had greater than mild tricuspid regurgitation or pulmonary regurgitation by intraoperative TEE or postoperative TTE.
Echocardiographic Data
Left ventricular ejection fraction (LVEF) was measured using either an M-mode or a two-dimensional modification of the method used by Quinones et al. If these measurements were inadequate, LVEF was estimated visually. The presence and severity of pulmonary regurgitation and tricuspid transprosthetic or periprosthetic regurgitation were noted. Doppler data were obtained from videotapes using the DigiView Image Management and Reporting System (release 3.6.3; Digisonics, Inc., Houston, TX) or from digital images using ProSolv software (ProSolv CardioVascular, Indianapolis, IN) for off-line analysis by one of the investigators (L.A.B).
The standard practice at our institution is to average three cycles of the left heart Doppler measurements for patients in sinus rhythm and to average at least five cycles for patients with atrial fibrillation or other irregular rhythms. For Doppler measurements of tricuspid prostheses, at least 9 or 10 cycles are usually averaged, regardless of rhythm, because of respiratory variation in the velocities. Whenever possible, attempts are made to use periods of physiologic heart rate and to match the 9 or 10 cycle lengths that are used for each parameter in patients with irregular heart rhythms. The number of cycles selected and the number of individual measurements used are approved by the supervising echocardiographer before inclusion in the final report. For this study, Doppler measurements of the SJM, CM, and SE mechanical tricuspid valve prostheses were recorded for nine consecutive cardiac cycles, and values were averaged for the first five cycles and for all nine cycles.
For the identification of possible mechanical tricuspid valve prosthesis dysfunction, threshold values for abnormal MG, E velocity, PHT, TVI TVP , and TVI TVP /TVI LVOT were determined by calculating the mean + 2 SD for each variable. The prosthesis EOA was calculated using the continuity equation (EOA = stroke volume/TVI TVP ) and the PHT method (EOA = 190/PHT). Continuous-wave Doppler measurements were used to determine PHT and TVI TVP .
Stroke volume was calculated as the product of the left ventricular outflow tract area and the TVI LVOT measured with pulsed-wave Doppler. The prosthesis performance index (PPI [ratio of the EOA of the prosthesis to the geometric orifice area of the prosthesis]) was calculated as the ratio of the EOA derived from the continuity equation to the geometric orifice area provided by the manufacturer: 3.67 cm 2 for the 27-mm, 4.41 cm 2 for the 29-mm, and 5.18 cm 2 for both the 31-mm and 33-mm SJM valves (St. Jude Medical, Inc.); 4.44 cm 2 for the 31-mm and 33-mm CM valves (Sorin Group); and 2.86 cm 2 , 3.24 cm 2 , and 3.46 cm 2 for the 30-mm (3M), 32-mm (4M), and 34-mm (5M) SE valves (Edwards Lifesciences, LLC), respectively. Other calculated variables included IEOA and TVI TVP /TVI LVOT .
Mechanical tricuspid valve prosthesis–patient mismatch (PPM) was assessed by calculating IOEA using the continuity equation. The threshold value for defining severe tricuspid PPM (IEOA ≤0.9 cm 2 /m 2 ) was chosen on the basis of results of previously published studies analyzing prostheses in the mitral valve position. This value was also used to delineate tricuspid PPM in our recently published study on tricuspid valve bioprostheses.
Statistical Analysis
The paired t test was used to compare measurements calculated by the continuity equation and the PHT method. Continuous variables were compared for the four valve size groups using analysis of variance. Differences were considered significant at P < .05. Significant differences were investigated by adjusting for multiple comparisons using the Student Newman–Keuls procedure.
Results
Clinical Characteristics
Characteristics of the 78 patients who had mechanical tricuspid valve prostheses implanted are summarized in Tables 1 to 3 . The most common indications for tricuspid valve replacement were nonrheumatic tricuspid regurgitation in 24 patients (31%), rheumatic heart disease in 16 patients (21%), carcinoid heart disease in 10 patients (13%), and unrepairable Ebstein anomaly in 8 patients (10%). A standard mechanical prosthesis was implanted in all patients, 64 (82%) of whom had TTE performed within the first week after tricuspid replacement. In the 78 patients, the heart rhythm was sinus in 44 (56%), paced in 19 (24%), and atrial fibrillation in 15 (19%). Of the 19 patients with paced heart rhythm, 15 had a permanent pacemaker implanted before tricuspid valve replacement surgery, 3 were paced with temporary pacing wires at the time of TTE, and 1 required placement of a permanent pacemaker with epicardial leads at the time of surgery.
| Characteristic | Prosthesis size ∗ | All patients ( N = 51) | ||||
|---|---|---|---|---|---|---|
| 27 mm ( n = 7) | 29 mm ( n = 7) | 31 mm ( n = 20) | 33 mm ( n = 17) | Mean ± SD | Range | |
| Age, y | 52 ± 13.7 | 50 ± 7.4 | 54 ± 13.3 | 60 ± 9.4 | 55 ± 11.8 | 18–76 |
| Women, No. (%) | 6 (86) | 6 (86) | 13 (65) | 10 (59) | 35 (69) | NA |
| Congenital heart disease, No. (%) | ||||||
| Any disease | 0 (0) | 0 (0) | 3 (15) | 1 (6) | 4 (8) | NA |
| Ebstein anomaly | 0 (0) | 0 (0) | 1 (5) | 0 (4) | 1 (2) | NA |
| Heart rate, beats/min | 80 ± 12.0 | 75 ± 12.7 | 78 ± 9.7 | 81 ± 9.6 | 79 ± 10.3 | 60–98 |
| Hemoglobin, g/dL | 10.3 ± 0.62 | 9.7 ± 1.16 | 10.1 ± 0.97 | 9.8 ± 0.89 | 10.0 ± 0.92 | 8.4–12.4 |
| Hematocrit, % | 30.2 ± 1.73 | 28.7 ± 3.68 | 29.3 ± 2.52 | 28.8 ± 2.51 | 29.2 ± 2.58 | 25.2–35.6 |
| BSA, m 2 | 1.67 ± 0.15 | 1.83 ± 0.27 | 1.83 ± 0.26 | 1.83 ± 0.21 | 1.81 ± 0.23 | 1.41–2.26 |
| LVEF, % † | 57 ± 13.9 | 58 ± 8.4 | 58 ± 9.4 | 59 ± 7.7 | 58 ± 9.2 | 40–76 |
| LVEF <50%, No. (%) | 2 (29) | 1 (14) | 1 (5) | 2 (12) | 6 (12) | NA |
| SV, mL | 61 ± 12.0 | 68 ± 22.3 | 75 ± 16.7 | 71 ± 13.3 | 71 ± 16.2 | 43–107 |
| SVI, mL/m 2 | 36 ± 5.6 | 37 ± 7.2 | 41 ± 8.9 | 39 ± 7.2 | 39 ± 7.8 | 27–59 |
| PHT, msec | 77 ± 14.6 ( n = 4) | 100 ± 35.2 ( n = 4) | 81 ± 13.5 ( n = 14) | 82 ± 18.8 ( n = 11) | 83 ± 19.1 ( N = 33) | 48–123 |
| MG, mm Hg | 2.4 ± 1.27 | 2.6 ± 1.13 | 3.3 ± 1.21 | 3.2 ± 1.24 | 3.0 ± 1.22 | 1–6 |
| E velocity, m/s | 1.1 ± 0.32 | 1.2 ± 0.21 | 1.4 ± 0.31 | 1.3 ± 0.22 | 1.3 ± 0.28 | 0.7–1.9 |
| TVI TVP , cm | 25 ± 7.0 | 31 ± 6.5 | 30 ± 5.1 | 30 ± 7.8 | 30 ± 6.6 | 16–46 |
| TVI TVP /TVI LVOT | 1.2 ± 0.33 | 1.4 ± 0.30 | 1.4 ± 0.23 | 1.5 ± 0.33 | 1.4 ± 0.29 | 0.8–2.3 |
| EOA | ||||||
| CON, cm 2 | 2.54 ± 0.64 | 2.20 ± 0.33 | 2.49 ± 0.45 | 2.46 ± 0.59 | 2.45 ± 0.51 | 1.51–3.78 |
| PHT, cm 2 | 2.52 ± 0.43 | 2.21 ± 1.17 | 2.41 ± 0.41 | 2.44 ± 0.54 | 2.41 ± 0.56 | 1.54–3.96 |
| IEOA | ||||||
| CON, cm 2 /m 2 | 1.52 ± 0.34 | 1.21 ± 0.13 | 1.38 ± 0.29 | 1.36 ± 0.36 | 1.37 ± 0.31 | 0.68–2.18 |
| PHT, cm 2 /m 2 | 1.54 ± 0.30 | 1.30 ± 0.93 | 1.36 ± 0.31 | 1.37 ± 0.29 | 1.38 ± 0.40 | 0.68–2.68 |
| PPI CON | 0.70 ± 0.16 | 0.50 ± 0.08 | 0.48 ± 0.09 | 0.47 ± 0.11 | 0.51 ± 0.13 | 0.29–0.99 |
∗ Values are mean ± SD or number (percentage) unless indicated otherwise.
† LVEF was obtained by visual estimate ( n = 34 [67%]), two-dimensional measurements ( n = 13 [25%]), or M-mode measurements ( n = 4 [8%]).
| Characteristic | Prosthesis size ∗ | All patients ( N = 17) | ||
|---|---|---|---|---|
| 31 mm ( n = 4) | 33 mm ( n = 13) | Mean ± SD | Range | |
| Age, y | 53 ± 3.9 | 46 ± 11.7 | 48 ± 10.8 | 30–66 |
| Women, No. (%) | 3 (75) | 6 (46) | 9 (53) | NA |
| Congenital heart disease, No. (%) | ||||
| All patients | 2 (50) | 4 (31) | 6 (35) | NA |
| Patients with Ebstein anomaly | 2 (50) | 4 (31) | 6 (35) | NA |
| Heart rate, beats/min | 75 ± 13.4 | 77 ± 9.2 | 77 ± 9.9 | 56–94 |
| Hemoglobin, g/dL | 9.8 ± 0.06 | 10.2 ± 1.15 | 10.1 ± 1.02 | 8.5–12.4 |
| Hematocrit, % | 28.3 ± 0.19 | 29.9 ± 3.33 | 29.5 ± 2.97 | 25–36 |
| BSA, m 2 | 1.93 ± 0.28 | 1.91 ± 0.28 | 1.92 ± 0.27 | 1.36–2.44 |
| LVEF, % † | 60 ± 3.1 | 55 ± 11.8 | 56 ± 10.6 | 30–68 |
| LVEF <50%, No. (%) | 0 (0) | 3 (23) | 3 (18) | NA |
| SV, mL | 81 ± 34.1 | 78 ± 17.4 | 79 ± 21.1 | 50−128 |
| SVI, mL/m 2 | 41 ± 11.5 | 42 ± 10.8 | 41 ± 10.6 | 28–59 |
| PHT, msec | 78 ( n = 1) | 98 ± 9.7 ( n = 5) | 95 ± 12.0 ( N = 6) | 78–108 |
| MG, mm Hg | 4.0 ± 1.63 | 3.4 ± 1.19 | 3.5 ± 1.28 | 2–6 |
| E velocity, m/s | 1.4 ± 0.19 | 1.2 ± 0.16 | 1.3 ± 0.17 | 0.9–1.6 |
| TVI TVP , cm | 40 ± 11.4 | 34 ± 7.3 | 35 ± 8.4 | 23–52 |
| TVI TVP /TVI LVOT | 1.9 ± 0.53 | 1.6 ± 0.33 | 1.7 ± 0.38 | 1.1–2.6 |
| EOA | ||||
| CON, cm 2 | 2.01 ± 0.51 | 2.33 ± 0.43 | 2.25 ± 0.46 | 1.60–2.97 |
| PHT, cm 2 | 2.44 | 1.95 ± 0.20 | 2.03 ± 0.27 | 1.76–2.44 |
| IEOA | ||||
| CON, cm 2 /m 2 | 1.04 ± 0.18 | 1.25 ± 0.35 | 1.20 ± 0.33 | 0.79–2.09 |
| PHT, cm 2 /m 2 | 1.09 | 1.04 ± 0.29 | 1.05 ± 0.26 | 0.80–1.53 |
| PPI CON | 0.45 ± 0.12 | 0.52 ± 0.10 | 0.51 ± 0.10 | 0.36–0.67 |
∗ Values are mean ± SD or number (percentage) unless indicated otherwise.
† LVEF was obtained by visual estimate ( n = 5 [29%]), two-dimensional measurements ( n = 7 [41%]), or M-mode measurements ( n = 5 [29%]).
| Characteristic | Prosthesis size ∗ | All patients ( N = 10) | |||
|---|---|---|---|---|---|
| 30 mm ( n = 1) | 32 mm ( n = 3) | 34 mm ( n = 6) | Mean ± SD | Range | |
| Age, y | 24 | 60 ± 10.4 | 63 ± 10.1 | 58 ± 15.1 | 24–70 |
| Women, No. (%) | 1 (100) | 1 (33) | 6 (100) | 8 (80) | NA |
| Congenital heart disease, No. (%) | |||||
| All patients, No. (%) | 0 (0) | 0 (0) | 1 (17) | 1 (10) | NA |
| Patients with Ebstein anomaly | 0 (0) | 0 (0) | 1 (17) | 1 (10) | NA |
| Heart rate, beats/min | 60 | 77 ± 11.4 | 77 ± 10.6 | 75 ± 10.9 | 60–90 |
| Hemoglobin, g/dL | 8.2 | 9.3 ± 0.91 | 9.4 ± 1.50 | 9.2 ± 1.25 | 7.5–11.3 |
| Hematocrit, % | 24.1 | 27.7 ± 3.10 | 27.9 ± 4.09 | 27.4 ± 3.58 | 22.7–33.3 |
| BSA, m 2 | 1.37 | 1.96 ± 0.18 | 1.67 ± 0.06 | 1.73 ± 0.21 | 1.37–2.17 |
| LVEF, % † | 65 | 59 ± 8.1 | 66 ± 6.6 | 64 ± 7.0 | 50–74 |
| LVEF <50%, No. (%) | NA | NA | NA | NA | NA |
| SV, mL | 85 | 69 ± 11.8 | 78 ± 20.1 | 76 ± 16.8 | 54–108 |
| SVI, mL/m 2 | 62 | 36 ± 8.3 | 47 ± 12.8 | 45 ± 13.0 | 29–66 |
| PHT, msec | 132 (n = 1) | NA ( n = 0) | 118 ± 32.9 ( n = 4) | 120 ± 29.2 ( N = 5) | 72–147 |
| MG, mm Hg | 5.0 | 4.0 ± 1.00 | 5.7 ± 1.63 | 5.1 ± 1.52 | 3–7 |
| E velocity, m/s | 1.5 | 1.5 ± 0.44 | 1.8 ± 0.28 | 1.7 ± 0.33 | 1.0–2.1 |
| TVI TVP , cm | 41 | 39 ± 14.2 | 44 ± 7.8 | 42 ± 9.2 | 29–55 |
| TVI TVP /TVI LVOT | 1.5 | 2.0 ± 0.68 | 1.9 ± 0.32 | 1.9 ± 0.42 | 1.5–2.8 |
| EOA | |||||
| CON, cm 2 | 2.07 | 1.87 ± 0.33 | 1.81 ± 0.48 | 1.86 ± 0.40 | 1.36–2.45 |
| PHT, cm 2 | 1.44 | NA | 1.75 ± 0.61 | 1.68 ± 0.55 | 1.29–2.64 |
| IEOA | |||||
| CON, cm 2 /m 2 | 1.51 | 0.96 ± 0.18 | 1.08 ± 0.29 | 1.09 ± 0.28 | 0.81–1.51 |
| PHT, cm 2 /m 2 | 1.05 | NA | 1.03 ± 0.31 | 1.04 ± 0.27 | 0.79–1.48 |
| PPI CON | 0.72 | 0.58 ± 0.10 | 0.52 ± 0.14 | 0.56 ± 0.13 | 0.39–0.72 |
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